1. Field of the Invention
The present invention relates to a method of manufacturing a molded article including a component insert-molded in a molding material mixed with solid powder.
2. Description of Related Art
Japanese Patent Application Laid-open No. 2007-136805 describes a method of manufacturing such a molded article.
In this method, a molded article is manufactured by agitating a casting material injected into a casting material cup, and injecting the agitated casting material into a casting die from the casting material cup. When the casting material is a molding material to be mixed with solid powder, the molding material and the solid powder mixed at a predetermined mixing ratio is injected into the casting material cup, and agitated so that the solid powder is dispersed in the molding material. Thereafter, the agitated mixture of the molding material and the solid powder is injected into the casting die from the casting material cup to mold a molded article.
However, the above method has a problem in that since the solid powder precipitates in the casting material cup, the mixing ratio of the solid powder deviates from die-to-die. Further, when the mixing ratio of the solid powder is high, since the viscosity of the agitated mixture of the molding material and the solid powder is high, it becomes difficult to inject the agitated mixture into the casting die from the casting material cup, causing the working hours to be lengthened. In addition, when the viscosity is higher, since the agitated mixture adheres more to the surface of the casting material cup, an amount of the agitate mixture which resides in the casting material cup and not injected into the casting die increases, as a result of which the yield ratio decreases.